1. Field of the Invention
The present invention relates to a liquid discharging head that discharges a liquid and to a method for producing the same.
2. Description of the Related Art
As a structure of a liquid discharging head, a structure including an element substrate and a supporting member is known. The element substrate is provided with a discharge opening row having a plurality of discharge openings for discharging a liquid as typified by ink. The supporting member is provided with a supply opening for supplying the liquid to the element substrate, and supports and is secured to the element substrate.
When producing the above-described liquid discharging head, the element substrate is bonded to the supporting member with an adhesive being provided therebetween. The precision of the position of the element substrate bonded to the supporting member considerably affects discharge characteristics of the liquid discharging head. Therefore, the element substrate is set at a predetermined position at the supporting member, and, in this state, is bonded to the supporting member.
Hitherto, as a method for positioning an element substrate in a direction (height direction) orthogonal to a surface of a supporting member to which the element substrate is bonded (hereunder referred to as “element-substrate bonding surface”), a positioning method for contacting the supporting member with and securing the supporting member to a jig, and, with a surface of the supporting member that contacts the jig being a reference surface, disposing the element substrate at a position situated at a predetermined height from the reference surface is known. In this positioning method, as regards the height of the element-substrate bonding surface of the supporting member, it is necessary to consider two types of variations mentioned below.
The first variation is a variation in the height of the element-substrate bonding surface from the reference surface. The second variation is a variation in the surface precision of the element-substrate bonding surface itself caused by, for example, warping of the supporting member.
Therefore, when the element substrate is bonded to the supporting member by the above-described positioning method, the position of the element substrate with respect to the element-substrate bonding surface is set so that the element substrate does not contact the supporting member even if these two variations are considered. Here, instead of the surface of the element substrate that opposes the supporting member (hereunder referred to as a “back surface”), a surface (hereunder referred to as a “front surface”) opposite to the back surface is disposed at a predetermined height from the reference surface. This makes it possible to increase the precision of the height of the front surface of the substrate element from the reference surface regardless of the two variations mentioned above and the variation in the thickness of the element substrate.
With an adhesive being applied to the supporting member up to a position that is higher than the position of the back surface of the element substrate whose height has been set, the adhesive is sufficiently pressed and spread over the back surface of the element substrate and is made to contact the entire back surface of the element substrate. Thereafter, by hardening the adhesive, the position of the element substrate with respect to the supporting member is fixed. This positioning method is hereunder referred to as “related art 1”.
In recent years, with a reduction in the size of an element substrate for the purpose of reducing the costs thereof, the area of the back surface of the element substrate to be bonded to the supporting member tends to be narrowed. In accordance with this, an application portion of an element-substrate bonding surface to which an adhesive can be applied also tends to be narrow, and the application portion, where the adhesive is applied, at the element-substrate bonding surface and an opening end of a supply opening tend to be close to each other. In this case, as the height at which the adhesive is applied is increased, it becomes more difficult to hold the adhesive on the element-surface bonding surface, as a result of which the adhesive tends to flow into the supply opening that is close to the application portion. This may occur even in the method disclosed in the related art 1.
That is, the front surface of the element substrate is disposed at a position that does not allow the back surface of the element substrate to contact the supporting member even if the variation in the height of the element-substrate bonding surface of the supporting member and the variation in the thickness of the element substrate are both considered, and the height at which the adhesive is applied is set so that, at this time, the adhesive on the supporting member is pressed and spread at the back surface of the element substrate and contacts the entire back surface of the element substrate. Therefore, even when the variation in the height of the element-substrate bonding surface to which the adhesive is actually applied is smaller than expected, it is necessary to apply the adhesive up to a set height at the element-substrate bonding surface. Consequently, the position where the adhesive is applied tends to be high.
Accordingly, with regard to the related art 1, a positioning method discussed in Japanese Patent Laid-Open No. 2012-240210 is available as a method for properly bonding an element substrate to a supporting member while reducing the height at which an adhesive is applied. The positioning method discussed in Japanese Patent Laid-Open No. 2012-240210 is a method in which a projection is provided at an element-substrate bonding surface of the supporting member and the element substrate is bonded to the supporting member at a position where the element substrate is caused to contact the projection. This method makes it possible to reduce the height at which the adhesive is applied even if the variation in the height of the element-substrate bonding surface is large.
However, in the positioning method discussed in Japanese Patent Laid-Open No. 2012-240210, since the element substrate is in contact with the projection of the element-substrate bonding surface of the supporting member, in addition to the variation in the height of the element-substrate bonding surface of the supporting member, the variation in the thickness of the element substrate also affects the precision of the height of the front surface of the element substrate from the supporting member. Therefore, compared to the related art 1, the positioning method discussed in Japanese Patent Laid-Open No. 2012-240210 has a problem in that the precision of the height of the front surface of the element substrate from the supporting member is reduced. On the other hand, the related art 1 has a problem in that, as mentioned above, the position to which the adhesive is applied is high.